Friday, February 26, 2010
Decent Event Today
The huge storm system affecting New England today is large enough to have adverse effects even for us back in SE Michigan. We should receive about 2-4" of snow today, with another inch possible tonight. Combine that with some very gusty winds, and we have a recipe for some very bad road conditions at times today. I expect a slow commute to school as a heavy band of snow moves through (schools in the more rural areas to our NE closed today). Anyways I figured this was worth a token mention, at least, as it will negatively impact the morning commute for sure and maybe the afternoon commute as well.
Monday, February 22, 2010
Tomorrow = Not So Good
The storm ended at around 4 p.m. today, and the main roads are already pretty good. I would expect that tonight the road crews will get to plowing the dirt roads, and by tomorrow morning, almost all of those will be cleared as well. By tomorrow morning, pretty much the only thing I would expect to not be plowed are the subdivisions and dead end side streets. This usually happens after a big storm, and we almost never get 2 snow days for a storm. Therefore, I am predicting that we will not have a snow day tomorrow.
Storm Total Snowfall
7.5" , within my 6-8" range.
Overall again am happy with how I forecasted this storm, predicted a snow day and we got one, predicted the total snowfall correctly...
Later I'll have my snow day prediction for tomorrow, I will probably predict no snow day but we do have a chance...
Overall again am happy with how I forecasted this storm, predicted a snow day and we got one, predicted the total snowfall correctly...
Later I'll have my snow day prediction for tomorrow, I will probably predict no snow day but we do have a chance...
Sunday, February 21, 2010
Final Call: 6-8" of snow...school?
Forecast Models:
All of the forecast models are in good agreement, so I will simply show the NAM and GFS, as they have the most detailed images.
NAM:
This image of the NAM shows moderate-heavy snowfall affecting SE Michigan between 7 a.m. and 1 p.m. tomorrow.
This image of the NAM shows a simulated radar image of the snow that will be affecting us tomorrow morning.
This image of the NAM shows storm total precipitation. This would give us around 7" of snow.
GFS:
This image of the GFS shows moderate-heavy snowfall affecting SE Michigan between 7 a.m. and 1 p.m. tomorrow.
This image of the GFS shows storm total precipitation. This would give us around 7" of snow.
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Snowfall Map:
The forecast models have been very consistent in showing the most precipitation falling in far SE Michigan. However, it now appears likely that the snow will mix with sleet in the early morning tomorrow near the Ohio Border. This will offset the higher precipitation amounts. In addition, there will be a lower snow-to-water ratio, which will also cut down on accumulations. Due to this, I will go with 5-7" for areas near the Ohio Border.
The most snow will likely fall between the I-94 and I-69 corridors. Here, lots of precipitation will still fall, but the snow will not mix with sleet tomorrow morning. Due to this, I will go with 6-8" for this area.
To the north of the I-69 corridor, precipitation amounts will start to taper off. Due to this, I will go with 5-7", and in the far northern counties, 4-6".
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Impacts From This Storm:
As you can see from the above radar image, this storm is on our doorstep. Snow will begin falling around midnight tonight, and increase in intensity as the night goes on. I would expect around 2" of snow to be on the ground by 6 a.m. tomorrow. The snow will be at its heaviest during the rush hour tomorrow morning, making for a very messy, slow, and dangerous commute. In fact, there could be some isolated instances of thundersnow tomorrow, if any convective bands of snow could form. In the heaviest bands of snow, snow could fall at a 1"/hour rate. Another 4-6" of snow will fall during the day tomorrow. After noontime tomorrow, the snow will gradually diminish in intensity, before stopping completely during the late afternoon hours tomorrow. However, I would expect that the roads would still be in poor shape for the evening commute tomorrow. By Tuesday Morning, the roads will probably be in better shape, as temperatures will be warm enough for road salt to be effective.
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Snow Day Prediction:
Monday: A good analog to this storm would be the 12/19/08 storm from last winter. Snow did not start falling until 5 a.m. in that storm, but it got very heavy very quickly, resulting in dangerous morning and evening commutes. Our school closed then, and I would expect it to close now. Despite only minor accumulations by rush hour tomorrow morning, moderate-heavy snow will be falling, making for a treacherous commute. In addition, 4-6 more inches of snow will fall during the day, which will not get cleared off of many roads. This would result in long bus delays on the ride home from school. Due to these factors, I am predicting that we will not have school tomorrow.
Tuesday: I would expect the storm to more or less end at around 5 p.m. tomorrow, giving the road crews around 12 hours to clear the roads. As I mentioned above, road salt will be effective in this situation, and it's not going to be an extremely large amount of snow to deal with. Therefore, I expect many of the roads to be cleared by Tuesday Morning, and will therefore lower the snow day grade for Tuesday to a "D" (small chance of a snow day, but not completely impossible).
All of the forecast models are in good agreement, so I will simply show the NAM and GFS, as they have the most detailed images.
NAM:
This image of the NAM shows moderate-heavy snowfall affecting SE Michigan between 7 a.m. and 1 p.m. tomorrow.
This image of the NAM shows a simulated radar image of the snow that will be affecting us tomorrow morning.
This image of the NAM shows storm total precipitation. This would give us around 7" of snow.
GFS:
This image of the GFS shows moderate-heavy snowfall affecting SE Michigan between 7 a.m. and 1 p.m. tomorrow.
This image of the GFS shows storm total precipitation. This would give us around 7" of snow.
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Snowfall Map:
The forecast models have been very consistent in showing the most precipitation falling in far SE Michigan. However, it now appears likely that the snow will mix with sleet in the early morning tomorrow near the Ohio Border. This will offset the higher precipitation amounts. In addition, there will be a lower snow-to-water ratio, which will also cut down on accumulations. Due to this, I will go with 5-7" for areas near the Ohio Border.
The most snow will likely fall between the I-94 and I-69 corridors. Here, lots of precipitation will still fall, but the snow will not mix with sleet tomorrow morning. Due to this, I will go with 6-8" for this area.
To the north of the I-69 corridor, precipitation amounts will start to taper off. Due to this, I will go with 5-7", and in the far northern counties, 4-6".
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Impacts From This Storm:
As you can see from the above radar image, this storm is on our doorstep. Snow will begin falling around midnight tonight, and increase in intensity as the night goes on. I would expect around 2" of snow to be on the ground by 6 a.m. tomorrow. The snow will be at its heaviest during the rush hour tomorrow morning, making for a very messy, slow, and dangerous commute. In fact, there could be some isolated instances of thundersnow tomorrow, if any convective bands of snow could form. In the heaviest bands of snow, snow could fall at a 1"/hour rate. Another 4-6" of snow will fall during the day tomorrow. After noontime tomorrow, the snow will gradually diminish in intensity, before stopping completely during the late afternoon hours tomorrow. However, I would expect that the roads would still be in poor shape for the evening commute tomorrow. By Tuesday Morning, the roads will probably be in better shape, as temperatures will be warm enough for road salt to be effective.
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Snow Day Prediction:
Monday: A good analog to this storm would be the 12/19/08 storm from last winter. Snow did not start falling until 5 a.m. in that storm, but it got very heavy very quickly, resulting in dangerous morning and evening commutes. Our school closed then, and I would expect it to close now. Despite only minor accumulations by rush hour tomorrow morning, moderate-heavy snow will be falling, making for a treacherous commute. In addition, 4-6 more inches of snow will fall during the day, which will not get cleared off of many roads. This would result in long bus delays on the ride home from school. Due to these factors, I am predicting that we will not have school tomorrow.
Tuesday: I would expect the storm to more or less end at around 5 p.m. tomorrow, giving the road crews around 12 hours to clear the roads. As I mentioned above, road salt will be effective in this situation, and it's not going to be an extremely large amount of snow to deal with. Therefore, I expect many of the roads to be cleared by Tuesday Morning, and will therefore lower the snow day grade for Tuesday to a "D" (small chance of a snow day, but not completely impossible).
Saturday, February 20, 2010
Snow Day Likely Monday, Possibly Another One Tuesday
I am glad to say that we now have a good amount of consistency with the models for the storm that will affect us during the entire day on Monday. It is looking good for 5-9" of snow to fall on Monday, with a good chance of a snow day on Monday & another chance for a snow day on Tuesday.
Let's look at some forecast models...
12z NAM looks good for a general 5-9" of snow across SE Michigan, with no precipitation type issues.
12z GFS, similar to the NAM.
12z GGEM, similar to the NAM & GFS for precipitation amounts but we could have a mixing issue as temperatures get above freezing for a bit.
12z ECMWF still has a general 5-9" of snow across SE Michigan, but the heaviest falls to the west.
Considering all this, I am going to make the most boring snowfall map ever. When taking into consideration all of the 12z models, it appears that a little more precipitation may fall in the far SE part of the state, but that they may have a little bit of an issue with the snow turning into sleet in the middle of the event. I will split the difference and just paint a general 5-9" of snow across the entire forecast area.
Currently, the timeframe of the storm is speeding up. I would now expect snow to begin falling at around 2 a.m. Monday Morning, with the heaviest snow falling during the day on Monday, before ending late Monday Evening. Considering this, I think a snow day now looks likely on Monday, and as such, I will raise the snow day grade to a "B" (snow day likely, but not a lock yet). Depending on how much snow falls and how quickly the storm ends, I could see another snow day occuring on Tuesday. However, there is a large difference between a 5" snowstorm that ends late Monday Evening, and a 9" snowstorm that ends late Monday Evening. Due to this, I will keep the snow day grade for Tuesday at a "C" (50/50, could break either way). If we end up getting in the upper range of my accumulation prediction, I could definitely see us getting 2 snow days.
Either way, a snow day looks likely Monday, as moderate/heavy snow will likely be falling by the time we have to go to school. Then, 3-6" of snow will probably be on the ground by the time school gets out Monday Afternoon, making the commute home a nightmare either way. Based on past trends, there is no reason to believe our school will be hesitant to call a snow day on Monday simply because there won't be a lot of snow on the ground by Monday Morning.
Bottom Line: 5-9" of snow, snow day likely Monday, snow day possible Tuesday.
Let's look at some forecast models...
12z NAM looks good for a general 5-9" of snow across SE Michigan, with no precipitation type issues.
12z GFS, similar to the NAM.
12z GGEM, similar to the NAM & GFS for precipitation amounts but we could have a mixing issue as temperatures get above freezing for a bit.
12z ECMWF still has a general 5-9" of snow across SE Michigan, but the heaviest falls to the west.
Considering all this, I am going to make the most boring snowfall map ever. When taking into consideration all of the 12z models, it appears that a little more precipitation may fall in the far SE part of the state, but that they may have a little bit of an issue with the snow turning into sleet in the middle of the event. I will split the difference and just paint a general 5-9" of snow across the entire forecast area.
Currently, the timeframe of the storm is speeding up. I would now expect snow to begin falling at around 2 a.m. Monday Morning, with the heaviest snow falling during the day on Monday, before ending late Monday Evening. Considering this, I think a snow day now looks likely on Monday, and as such, I will raise the snow day grade to a "B" (snow day likely, but not a lock yet). Depending on how much snow falls and how quickly the storm ends, I could see another snow day occuring on Tuesday. However, there is a large difference between a 5" snowstorm that ends late Monday Evening, and a 9" snowstorm that ends late Monday Evening. Due to this, I will keep the snow day grade for Tuesday at a "C" (50/50, could break either way). If we end up getting in the upper range of my accumulation prediction, I could definitely see us getting 2 snow days.
Either way, a snow day looks likely Monday, as moderate/heavy snow will likely be falling by the time we have to go to school. Then, 3-6" of snow will probably be on the ground by the time school gets out Monday Afternoon, making the commute home a nightmare either way. Based on past trends, there is no reason to believe our school will be hesitant to call a snow day on Monday simply because there won't be a lot of snow on the ground by Monday Morning.
Bottom Line: 5-9" of snow, snow day likely Monday, snow day possible Tuesday.
Good model agreement for the storm
It's late, and I'm too tired to post images, so I'll save that for tomorrow afternoon's post, but I will say that we have good model agreement for this storm now.
The NAM, GFS, GGEM, and ECMWF models all give us significant precipitation with this storm. Even the lesser models are in decent agreement with this now. So, at this time, I would say that there is no chance that this storm will miss us to the south. The main thing I think we would have to worry about this point is for some ice, sleet, or rain to mix in with the snow, but so far, only the GGEM has shown the potential for this to happen.
However, all in all, I have a pretty high confidence in a Winter Storm Warning event for our area. To stay on the safe side for now (due to potential issues such as dry slotting or mixing), I will call for 5-9" of snow with this storm. However, if we do not have precipitation type issues, accumulations will likely have to be adjusted upwards.
The bottom line is that barring another major shift to the northwest in the storm track, I would expect at least 5" of snow with this storm, and in all likelihood, I would think more than that would fall.
With regards to snow day chances, it's kind of unclear at this point. This will likely be a long duration snowstorm (18-24 hours) so I believe it is likely that we will get at least one snow day with this storm. Earlier today, I stated it was more likely that we would get Tuesday off with this storm, if we got a snow day. However, the starting time for this storm has sped up. The storm is now expected to start early Monday Morning, and finish late Monday Evening. With this timing, I am really kind of unsure as to which day we would be more likely to get a snow day.
For now, to split the difference, I will make the snow day grade for both Monday and Tuesday a "C", but I do believe that if everything stays the same with this storm, we will get at least one snow day, with an outside shot at two.
Again, it should be a fun few days tracking this storm. The next post will be up sometime tomorrow afternoon...
The NAM, GFS, GGEM, and ECMWF models all give us significant precipitation with this storm. Even the lesser models are in decent agreement with this now. So, at this time, I would say that there is no chance that this storm will miss us to the south. The main thing I think we would have to worry about this point is for some ice, sleet, or rain to mix in with the snow, but so far, only the GGEM has shown the potential for this to happen.
However, all in all, I have a pretty high confidence in a Winter Storm Warning event for our area. To stay on the safe side for now (due to potential issues such as dry slotting or mixing), I will call for 5-9" of snow with this storm. However, if we do not have precipitation type issues, accumulations will likely have to be adjusted upwards.
The bottom line is that barring another major shift to the northwest in the storm track, I would expect at least 5" of snow with this storm, and in all likelihood, I would think more than that would fall.
With regards to snow day chances, it's kind of unclear at this point. This will likely be a long duration snowstorm (18-24 hours) so I believe it is likely that we will get at least one snow day with this storm. Earlier today, I stated it was more likely that we would get Tuesday off with this storm, if we got a snow day. However, the starting time for this storm has sped up. The storm is now expected to start early Monday Morning, and finish late Monday Evening. With this timing, I am really kind of unsure as to which day we would be more likely to get a snow day.
For now, to split the difference, I will make the snow day grade for both Monday and Tuesday a "C", but I do believe that if everything stays the same with this storm, we will get at least one snow day, with an outside shot at two.
Again, it should be a fun few days tracking this storm. The next post will be up sometime tomorrow afternoon...
Friday, February 19, 2010
Lookin' Goooood :)
I will post a full update by midnight tonight, but right now I'll just say that it's looking good for another nice snowstorm in SE Michigan. As of right now, it definitely seems like we're going to get affected by a storm, the main question is whether we will changeover to ice or rain rain at some point, which would obviously cut down on accumulations. Right now, it looks like that probably won't happen, and that accumulations of 5-9" look likely. If we can get into the heaviest bands, 10"+ is even possible. Obviously more will be known about this storm in the next couple of days, and I will have a lot more confidence in any one solution by tomorrow night. Tuesday looks decent for a snow day right now.
Thursday, February 18, 2010
Forecast Model Madness
To get an idea of the disagreement going on with this storm, take a look at the GFS (top image) versus the ECMWF (bottom image). The GFS is hundreds of miles south, and would result in nothing happening in SE Michigan, while the ECMWF's scenario has us getting a nice winter storm.
This disagreement likely will not be settled until this weekend...trust me when I say that I do not know what is going to happen with this storm yet. There's a chance for a storm, that's all I'll say for now.
Also FWIW I was busy tonight (Thursday Night) so no time for a new post. Basically, not much has changed, there is still large disagreement among the models. I'll have a longer post up by midnight tomorrow as long as there is still a chance that the storm will affect us.
This disagreement likely will not be settled until this weekend...trust me when I say that I do not know what is going to happen with this storm yet. There's a chance for a storm, that's all I'll say for now.
Also FWIW I was busy tonight (Thursday Night) so no time for a new post. Basically, not much has changed, there is still large disagreement among the models. I'll have a longer post up by midnight tomorrow as long as there is still a chance that the storm will affect us.
Wednesday, February 17, 2010
Next
Seems like there is a possibility for another storm around Monday...unlike the last storm, I am far from confident that this one will affect us, but it's still worth blogging about, so I'll look into it a little more tonight.
Tuesday, February 9, 2010
1st Snow Day of the Year :)
Obviously very satisfied with my forecasting leading up to this storm as I started mentioning this one as early as Friday, and gave it an above average snowfall grade as early as Saturday.
Otherwise, this will be my final update...radar still shows a swath of precipitation over SE Michigan, and we already have nearly 5" of snow, I have no fear that we reach 7" with this storm.
Tomorrow I may edit this with a map comparing actual totals to my forecasted totals.
Otherwise, this will be my final update...radar still shows a swath of precipitation over SE Michigan, and we already have nearly 5" of snow, I have no fear that we reach 7" with this storm.
Tomorrow I may edit this with a map comparing actual totals to my forecasted totals.
Update #2
Heaviest bands yet are about to move through here...in the next 6 hours I would think 4-5" fall...storm total of 7-9" seems pretty good to predict.
Update #1
Already almost 3" here at my house, and with hours of moderate/heavy snow coming up, don't see any way we end up with less than 7"...check out the radar below.
Obviously minimum of 7" is well more than enough for a snow day...it's now not a matter of if, but when, they call school. Looks like my forecast of 6-10" will verify quite well...and I still see some isolated jackpot totals over 1' south of us.
Obviously minimum of 7" is well more than enough for a snow day...it's now not a matter of if, but when, they call school. Looks like my forecast of 6-10" will verify quite well...and I still see some isolated jackpot totals over 1' south of us.
Final Snow Map and Prediction
I still like my map from last night, only change I will make is to increase high end accumulations between Bay City and I-69 from 7" to 8". This is because (a) forecast models last night came in a little wetter for some of that area (b) lake enhancement from Lake Huron could increase totals by 1-2" in the lakeshore counties from what they would otherwise be. Therefore I feel it's prudent to put in an area of 4-8". Other than that, everything seems to be on track with the storm. The National Weather Service moved an inch closer to my predictions, but one of us still has to be wrong, especially south of Detroit where they have 5-9" and I have 8-12". We'll see, I still think they're lowballing totals a little bit.
Here's my final map:
In addition, there's no point in waiting until tonight...so I'll just predict right now that we will get a snow day tomorrow. I can't possibly see how we wouldn't, even if the lower totals forecasted by the National Weather Service are correct.
I'll have one or two new posts up tonight, first one probably between 6:00 and 7:00 p.m.
Here's my final map:
In addition, there's no point in waiting until tonight...so I'll just predict right now that we will get a snow day tomorrow. I can't possibly see how we wouldn't, even if the lower totals forecasted by the National Weather Service are correct.
I'll have one or two new posts up tonight, first one probably between 6:00 and 7:00 p.m.
Monday, February 8, 2010
Yes, I am forecasting much higher than the NWS...hear me out
Needless to say, I was really surprised when I saw that the National Weather Service dropped our forecasted accumulations to 4-7"...and to be honest, I can't really find a good reason why they're doing that. I can agree with them that there will be some dry air to overcome at the onset of the storm, but since the heaviest snow is going to fall around 12 hours after the storm begins, I don't think the dry air will cut into accumulations much at all. They see a south trend with the precipitation shown by the forecast models, but I haven't seen any model move far enough south to knock us out of the 6-10" range. There has been a slight southward trend in the models over the last day or so, and seasonal trends support the storm moving a little further north than is currently depicted by the models (this last minute northward trend has happened to every storm this year that I can remember). Therefore, I'm really questioning why the National Weather Service dropped our totals, especially when the National Weather Service in Grand Rapids forecasts 6-10" to fall in the counties to the west of us, and 8-12" to fall in the counties to the southwest of us. I think that is a more realistic depiction of what will actually happen.
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Forecast Model Images:
NAM
This image of the NAM shows a heavy band of snow impacting the M-59 and I-94 corridors early Wednesday Morning:
This image of the NAM shows that band of snow affecting us in simulated radar form:
This image of the NAM shows storm total precipitation. It has moved south from yesterday, but if you read my discussion yesterday, you'll note that I was disregarding the NAM in the first place because it was too far north. It is simply moving into model consensus...
GFS
This image of the GFS shows moderate-to-heavy snowfall impacting all of SE Michigan early Wednesday morning. Note the tightly packed pressure gradient, which will result in very windy conditions which will blow the snow around, with the end result being huge snow drifts.
This image of the GFS shows storm total precipitation...note how similar it is to the NAM...
GGEM
This image of the GGEM shows moderate-to-heavy snowfall impacting all of SE Michgian early Wednesday morning.
This image of the GGEM show storm total precipitation...a bit drier than the NAM & GFS, but still has the dark blue over us, which equates to 6" minimum
ECMWF
Once again, no pics, but apparently it also is a bit drier than the NAM & GFS...still showing at least 6" of snow for us...
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Forecast Model Preference:
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Forecast Model Images:
NAM
This image of the NAM shows a heavy band of snow impacting the M-59 and I-94 corridors early Wednesday Morning:
This image of the NAM shows that band of snow affecting us in simulated radar form:
This image of the NAM shows storm total precipitation. It has moved south from yesterday, but if you read my discussion yesterday, you'll note that I was disregarding the NAM in the first place because it was too far north. It is simply moving into model consensus...
GFS
This image of the GFS shows moderate-to-heavy snowfall impacting all of SE Michigan early Wednesday morning. Note the tightly packed pressure gradient, which will result in very windy conditions which will blow the snow around, with the end result being huge snow drifts.
This image of the GFS shows storm total precipitation...note how similar it is to the NAM...
GGEM
This image of the GGEM shows moderate-to-heavy snowfall impacting all of SE Michgian early Wednesday morning.
This image of the GGEM show storm total precipitation...a bit drier than the NAM & GFS, but still has the dark blue over us, which equates to 6" minimum
ECMWF
Once again, no pics, but apparently it also is a bit drier than the NAM & GFS...still showing at least 6" of snow for us...
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Forecast Model Preference:
All models show a near-perfect storm track for SE Michigan to get heavy snows, there has been almost no change since yesterday. Models have basically stayed the same with precipitation (except for the NAM which went south to the model consensus). There is now a tight model consensus for where the heaviest precipitation will occur, which is south of I-696 and into NW Ohio. I have no preference on the track, for precipitation, I will use a blend of all four of the major models. Really, it's getting to the point in the storm where models become almost useless, and by tomorrow, we'll be nowcasting...
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Snow Map:
Once again, I am glad I used 15:1 snow-to-water ratios (for a further discussion on ratios, look at the discussions below), as it looks like these may not even be met. I always like to stay conservative on ratios, so for this map, I will stick to 13:1 ratios.
For Detroit south, I will assume they will get anywhere from 0.65-0.95" of water equivalent. With 13:1 ratios, this equates to anywhere from 8.45-12.35" of snow. I'll just round those down, for a forecast of 8-12". I still feel some areas with persistent heavier banding could get over a foot, so I will include the "Locally Higher" label.
From I-69 to Detroit, I will assume we get anywhere from 0.5-0.75" of water equivalent. With 13:1 ratios, this equates to anywhere from 6.5-9.75" of snow. To give myself some breathing room, I'll round the 6.5" down and the 9.75" up, for a forecast of 6-10". Come tomorrow morning, when I make my final prediction, I may shave an inch of the bottom or the top of the forecast, depending on nowcasting trends...
From I-69 up to Bay City, I will assume they will get anywhere from 0.3-0.5" of water equivalent. With 13:1 ratios, this equates to anywhere from 3.9-6.5" of snow. I'll round the 3.9" up to 4", and round the 6.5" up to 7" as I have a hard time believing amounts will diminish extremely quickly.
North of Bay City, I'll cut amounts just a little bit more due to the slight south trend, for 3-6". Due to enhancement from Lake Huron, I will not cut amounts in the Thumb, opting to keep them at 4-7".
This is reflected in the following snow map:
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Snow Day Chances:
My thinking still hasn't changed. It's early February, and we haven't had a snow day. Therefore, I feel anywhere from 5" on up gets us a snow day. In fact, due to the blowing and drifting of snow, 4" may do the trick. However, I still find the National Weather Service's forecast quite curious, and am still quite confident we end up with 6+" of snow.
Snow will start around noon tomorrow. This event will start slowly, but will pick up steam rapidly in the evening, with moderate-to-heavy snow falling after 8 p.m. tomorrow night and continuing on into the morning hours on Wednesday. Rush hour traffic will be severely impacted, as the road comission simply will not be able to keep up with the snow. Adding to the headache will be 20-30 mph winds that will cause near-whiteout conditions at times, and cause snow drifts up to 2' high, rendering some back roads nearly impassable. In fact, some weather outlets have hinted at gusts up to 40 mph as the storm departs. Considering all this, there is almost no doubt in my mind that we will have a snow day Wednesday. I have no reason not to raise the snow day grade to an "A" (near 100% chance of a snow day) for the first time this year. Everything looks set for our first snow day to occur on Wednesday. Hope everyone enjoys the storm.
Sunday, February 7, 2010
Tuesday/Wednesday Storm = Love
Another couple of model runs, and even more confidence that the storm that occurs Tuesday/Wednesday is going to be "the one" for the winter of 2009-10, at least so far. If you want to know what in the atmosphere is causing this storm to occur, scroll down to the last few posts...today I'm going to focus on what the different models are showing. Then, I'll use the current model guidance to make a preliminary snowfall map and state my thoughts on the chances of a snow day.
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Forecast Model Images:
NAM
This image of the NAM shows a very heavy band of snow affecting anyone from M-59 north in SE Michigan from 1 a.m. - 7 a.m. Wednesday Morning:
This image of the NAM shows that band affecting us in simulated radar form, just another look at the band of snow:
Finally, this image of the NAM shows storm total snowfall. It paints the highest accumulations (likely 10-15") over the M-59 and I-69 corridors:
GFS
This image of the GFS shows moderate-to-heavy snow affecting everyone in NW Ohio and SE Michigan. Note the tighly packed black lines. This represents a strong pressure gradient and the likely result would be near blizzard or even low end blizzard conditions from 1 a.m. - 7 a.m. Wednesday Morning:
This image of the GFS shows storm total snowfall. It paints the highest accumulations (likely 10-15") over the I-94 corridor down to NW Ohio:
GGEM
This image of the GGEM shows a band of heavy snow impact NW Ohio. Moderate snow is still falling in SE Michigan:
This image of the GGEM shows storm total snowfall. It paints the highest accumulations (likely 11-17") over NW Ohio:
ECMWF
No pictures with the ECMWF due to its horrible resolution, but it is similar to the GFS in its precipitation output.
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Forecast Model Preference:
The forecast models are tightly clustered with regards to track, generally tracking a low up Western Ohio passing just east of or over Detroit, before the energy transfers to a secondary low on the east coast. Due to the high confidence in the track, I will take the "middle of the road" models when it comes to precipitation. This means disregarding the further north NAM and further south GGEM as outliers when it comes to precipitation, and relying on the ECMWF and GFS.
Therefore, for my snow map, I will assume that the highest precipitation totals will be from the I-94 corridor south, with precipitation amounts gradually tapering off as you head to the north.
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Snow Map:
With my snow map, I will assume a general 15:1 snow-to-water ratio, just to be on the safe side. Ratios could definitely be higher, but ratios have fallen short of what has been expected too often for me to feel comfortable using anything higher than 15:1.
For Detroit south, I will assume they will get anywhere from 0.75 - 1.0" of water equivalent. With a 15:1 ratio, this is equivalent to anywhere from 11.25-15" of snow. Due to the possibility that higher precipitation amounts could shift, I will give them a low end accumulation of 8". I also see any accumulations of over 14" being highly localized. They could happen, but to keep it safe 60 hours out, I will forecast 8-14" with a "Locally Higher" label from I-94 south.
Between Saginaw and Detroit, I will assume we will get anywhere from 0.5-0.7" of water equivalent. With a 15:1 ratio, this is equivalent to anywhere from 7.5-10.5" of snow. Once again, due to the possibility that higher precipitation amounts could shift, I will give us a low end accumulation of 6". Considering it's still 60 hours out, I will round down the 10.5" to a high end of 10" of accumulation. Therefore, my forecast for this area will be 6-10" of snow.
North of Saginaw, I will assume they will get anywhere from 0.3-0.5" of water equivalent. With a 15:1 ratio, this is equivalent to anywhere from 4.5-7.5" of snow. North of Saginaw, any shift to the north or south could have a fairly significant effect on accumulations. Therefore I'll round the low end down and the high end up for a forecast of 4-8" of snow.
This is reflected in the following snow map:
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Snow Day Chances:
The timeframe of this storm has moved back even a little further. Snow is now expected to start Tuesday Afternoon, continuing through Wednesday Afternoon, with the heaviest snow falling early Wednesday Morning. Obviously, this is pretty much perfect timing for a snow day, and if precipitation ends late enough on Wednesday, we could get two...but for now I will only talk about the snow day chances on Wednesday.
Considering it's early February, and we haven't had a snow day yet, I think anywhere from 5"+ could get us a snow day. Obviously, the low end of my snowfall forecast is for 6" of snow, so the amount of snow should also suffice.
Finally, one more thing in our favor is that at the height of the storm, near blizzard conditions are likely. I could easily see winds gusting up to 30-35 mph with a tight air pressure gradient over our region. This will result in whiteout conditions, and extensive blowing and drifting of snow. I would expect some drifts to be over 2'.
Obviously, the road commission is not going to be able to keep up with this mess. The only reason I won't move the snow day grade to an "A" is that we're still over 2 days out, but if everything looks the same at this time tomorrow, I will move it to an "A". For now though, I'll keep it at a "B" (good chance of a snow day, but not a lock yet). This is pretty much as confident as I'll ever be for a storm that's still 2 days away. I'd expect the National Weather Service to have Winter Storm Watches up either this afternoon or tomorrow morning. Should be a fun next few days tracking this one...
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Forecast Model Images:
NAM
This image of the NAM shows a very heavy band of snow affecting anyone from M-59 north in SE Michigan from 1 a.m. - 7 a.m. Wednesday Morning:
This image of the NAM shows that band affecting us in simulated radar form, just another look at the band of snow:
Finally, this image of the NAM shows storm total snowfall. It paints the highest accumulations (likely 10-15") over the M-59 and I-69 corridors:
GFS
This image of the GFS shows moderate-to-heavy snow affecting everyone in NW Ohio and SE Michigan. Note the tighly packed black lines. This represents a strong pressure gradient and the likely result would be near blizzard or even low end blizzard conditions from 1 a.m. - 7 a.m. Wednesday Morning:
This image of the GFS shows storm total snowfall. It paints the highest accumulations (likely 10-15") over the I-94 corridor down to NW Ohio:
GGEM
This image of the GGEM shows a band of heavy snow impact NW Ohio. Moderate snow is still falling in SE Michigan:
This image of the GGEM shows storm total snowfall. It paints the highest accumulations (likely 11-17") over NW Ohio:
ECMWF
No pictures with the ECMWF due to its horrible resolution, but it is similar to the GFS in its precipitation output.
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Forecast Model Preference:
The forecast models are tightly clustered with regards to track, generally tracking a low up Western Ohio passing just east of or over Detroit, before the energy transfers to a secondary low on the east coast. Due to the high confidence in the track, I will take the "middle of the road" models when it comes to precipitation. This means disregarding the further north NAM and further south GGEM as outliers when it comes to precipitation, and relying on the ECMWF and GFS.
Therefore, for my snow map, I will assume that the highest precipitation totals will be from the I-94 corridor south, with precipitation amounts gradually tapering off as you head to the north.
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Snow Map:
With my snow map, I will assume a general 15:1 snow-to-water ratio, just to be on the safe side. Ratios could definitely be higher, but ratios have fallen short of what has been expected too often for me to feel comfortable using anything higher than 15:1.
For Detroit south, I will assume they will get anywhere from 0.75 - 1.0" of water equivalent. With a 15:1 ratio, this is equivalent to anywhere from 11.25-15" of snow. Due to the possibility that higher precipitation amounts could shift, I will give them a low end accumulation of 8". I also see any accumulations of over 14" being highly localized. They could happen, but to keep it safe 60 hours out, I will forecast 8-14" with a "Locally Higher" label from I-94 south.
Between Saginaw and Detroit, I will assume we will get anywhere from 0.5-0.7" of water equivalent. With a 15:1 ratio, this is equivalent to anywhere from 7.5-10.5" of snow. Once again, due to the possibility that higher precipitation amounts could shift, I will give us a low end accumulation of 6". Considering it's still 60 hours out, I will round down the 10.5" to a high end of 10" of accumulation. Therefore, my forecast for this area will be 6-10" of snow.
North of Saginaw, I will assume they will get anywhere from 0.3-0.5" of water equivalent. With a 15:1 ratio, this is equivalent to anywhere from 4.5-7.5" of snow. North of Saginaw, any shift to the north or south could have a fairly significant effect on accumulations. Therefore I'll round the low end down and the high end up for a forecast of 4-8" of snow.
This is reflected in the following snow map:
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Snow Day Chances:
The timeframe of this storm has moved back even a little further. Snow is now expected to start Tuesday Afternoon, continuing through Wednesday Afternoon, with the heaviest snow falling early Wednesday Morning. Obviously, this is pretty much perfect timing for a snow day, and if precipitation ends late enough on Wednesday, we could get two...but for now I will only talk about the snow day chances on Wednesday.
Considering it's early February, and we haven't had a snow day yet, I think anywhere from 5"+ could get us a snow day. Obviously, the low end of my snowfall forecast is for 6" of snow, so the amount of snow should also suffice.
Finally, one more thing in our favor is that at the height of the storm, near blizzard conditions are likely. I could easily see winds gusting up to 30-35 mph with a tight air pressure gradient over our region. This will result in whiteout conditions, and extensive blowing and drifting of snow. I would expect some drifts to be over 2'.
Obviously, the road commission is not going to be able to keep up with this mess. The only reason I won't move the snow day grade to an "A" is that we're still over 2 days out, but if everything looks the same at this time tomorrow, I will move it to an "A". For now though, I'll keep it at a "B" (good chance of a snow day, but not a lock yet). This is pretty much as confident as I'll ever be for a storm that's still 2 days away. I'd expect the National Weather Service to have Winter Storm Watches up either this afternoon or tomorrow morning. Should be a fun next few days tracking this one...
Saturday, February 6, 2010
Still looking good for the Tuesday/Wednesday storm
We are only 84 hours out from what I believe will be the most significant snow event we have seen thus far for this winter. The overall long-term pattern still doesn't favor our area, but luckily enough, a very strong upper level low will drop south and phase with another system, resulting in what will likely be a nice snow event for our area.
Last night, I mentioned that current model trends place SE Michigan in the dryslot with the storm, which would cut down on accumulations. Now, the models have trended towards placing SE Michigan in the deformation zone of the storm, which would result in a prolonged period of heavier snow, with higher accumulations the result. The 12z GFS (top image) and 12z NAM (bottom image) illustrate this nicely.
There is now a strong agreement among four of the major models (GFS, NAM, ECMWF, GGEM) that SE Michigan will not get dryslotted with this storm. Obviously, this could change, but right now the trends are favoring us.
So, let's talk about how this storm should play out for us, and what it means w/ regards to a snow day. Since last night, trends have been to slow down this meat of this storm just a bit. Snow should still start around noon on Tuesday, but the heaviest snow is now expected to fall early on Wednesday morning, which is perfect timing. The storm will likely wind down around or shortly after noon Wednesday. Obviously, the timing is good for a snow day, but what about the amount of snow that is going to fall?
Happily, I can say that the amount of snow that is going to fall will also likely be enough for a snow day. The GFS and ECMWF have been consistent in giving us a good amount of precipitation with this storm, and the GGEM, while not as wet as the GFS or ECMWF yet, has been trending in our favor. The NAM is currently the driest of the models, but I think even it would give us enough precipitation for 4+" of snow. And considering the strength of the upper level low that will be moving just to our south, I tend to think the NAM is slightly underplaying the amount of precipitation we will receive from this storm.
A couple of other factors should also make this system a good snow producer. As I mentioned earlier, the models have trended towards putting SE Michigan under the heaviest band of snowfall with this system, known as the deformation zone. The track of the upper level low shown by the GFS, NAM, and ECMWF (through Central Illinois, Indiana, and Ohio) is just about perfect to put SE Michigan in the heaviest band of snowfall.
Also, as I mentioned last night, the snowfall ratios with this system will likely be higher than normal. What do snowfall ratios do w/ regards to accumulations? Here's what I posted last night...
"As a basic example [this won't necessarily be exactly what happens with this storm], if we got .5" of water falling with 10:1 ratios, that would result in 5" of snow. With 20:1 ratios, .5" of water would result in 10" of snow."
Anyways, with the strong upper level low pulling down cold arctic air, we should have no problem achieving 15:1 ratios with this event, and they could be even higher, although I will currently forecast assuming a 15:1 snow ratio.
All these things are shaping up to give us a good chance at a snow day on Wednesday. I currently expect this storm to give us anywhere from 5-11" of snow (I will whittle down this range of accumulations as we get closer to the storm). This storm will have a favorable timing, with the heaviest snow likely falling between midnight and 6 a.m. Wednesday, leaving the road commission little time to clear it out of the way. Not only that, but I expect powdery snow and high winds to blow the snow around, likely resulting in drifts of over 1'. Also, snow will likely still be falling during the morning commute Wednesday.
Combine all of the above with the fact that it's February, and we haven't had a snow day yet, and I am willing to raise the snow day grade to a B (good chance of a snow day, but not a lock) for Wednesday. Watching this storm unfold over the next few days should be very fun...
Last night, I mentioned that current model trends place SE Michigan in the dryslot with the storm, which would cut down on accumulations. Now, the models have trended towards placing SE Michigan in the deformation zone of the storm, which would result in a prolonged period of heavier snow, with higher accumulations the result. The 12z GFS (top image) and 12z NAM (bottom image) illustrate this nicely.
There is now a strong agreement among four of the major models (GFS, NAM, ECMWF, GGEM) that SE Michigan will not get dryslotted with this storm. Obviously, this could change, but right now the trends are favoring us.
So, let's talk about how this storm should play out for us, and what it means w/ regards to a snow day. Since last night, trends have been to slow down this meat of this storm just a bit. Snow should still start around noon on Tuesday, but the heaviest snow is now expected to fall early on Wednesday morning, which is perfect timing. The storm will likely wind down around or shortly after noon Wednesday. Obviously, the timing is good for a snow day, but what about the amount of snow that is going to fall?
Happily, I can say that the amount of snow that is going to fall will also likely be enough for a snow day. The GFS and ECMWF have been consistent in giving us a good amount of precipitation with this storm, and the GGEM, while not as wet as the GFS or ECMWF yet, has been trending in our favor. The NAM is currently the driest of the models, but I think even it would give us enough precipitation for 4+" of snow. And considering the strength of the upper level low that will be moving just to our south, I tend to think the NAM is slightly underplaying the amount of precipitation we will receive from this storm.
A couple of other factors should also make this system a good snow producer. As I mentioned earlier, the models have trended towards putting SE Michigan under the heaviest band of snowfall with this system, known as the deformation zone. The track of the upper level low shown by the GFS, NAM, and ECMWF (through Central Illinois, Indiana, and Ohio) is just about perfect to put SE Michigan in the heaviest band of snowfall.
Also, as I mentioned last night, the snowfall ratios with this system will likely be higher than normal. What do snowfall ratios do w/ regards to accumulations? Here's what I posted last night...
"As a basic example [this won't necessarily be exactly what happens with this storm], if we got .5" of water falling with 10:1 ratios, that would result in 5" of snow. With 20:1 ratios, .5" of water would result in 10" of snow."
Anyways, with the strong upper level low pulling down cold arctic air, we should have no problem achieving 15:1 ratios with this event, and they could be even higher, although I will currently forecast assuming a 15:1 snow ratio.
All these things are shaping up to give us a good chance at a snow day on Wednesday. I currently expect this storm to give us anywhere from 5-11" of snow (I will whittle down this range of accumulations as we get closer to the storm). This storm will have a favorable timing, with the heaviest snow likely falling between midnight and 6 a.m. Wednesday, leaving the road commission little time to clear it out of the way. Not only that, but I expect powdery snow and high winds to blow the snow around, likely resulting in drifts of over 1'. Also, snow will likely still be falling during the morning commute Wednesday.
Combine all of the above with the fact that it's February, and we haven't had a snow day yet, and I am willing to raise the snow day grade to a B (good chance of a snow day, but not a lock) for Wednesday. Watching this storm unfold over the next few days should be very fun...
Friday, February 5, 2010
Finally, the event to break our snow drought is here
With the massive storm that is bearing down on DC, Baltimore, and Philly this weekend, it's the perfect time for the next storm to sneak under the radar and affect us...
Finally, for the first time in a while this winter, it appears that two systems will fully phase, allowing it to track further north than previous systems, and therefore affect us. The forecast models are in strong agreement on dropping an upper level low down from the Hudson Bay area and phasing it with a southern stream wave. This full phase will allow this system to track further north than the last two systems, despite another energy transfer occurring. This time around, the primary low pressure system will likely track from Mississippi to Michigan, before transferring energy to a secondary low that will move up the east coast.
What this means is that we will finally get some snow. And probably a decent amount of it, at that. The last four runs of the GFS model have been consistent in putting out a decent amount of precipitation for our area. Other models, such as the ECMWF and GGEM, are in agreement with our area getting a decent amount of snow out of this system.
Exactly how much snow we will get with this storm remains highly up in the air. If the low pressure system tracks directly over us, we will get dryslotted after the initial band of snow, which will cut down on accumulations. That was what the forecast models showed earlier, but they have trended a bit to the SE, putting us in the deformation band (heavier band) of snow, which would maximize our accumulations. The former is the worst option and the latter is the best option. The middle of the road option is that the low tracks even further to the SE, putting us out of the deformation band but also out of the dryslot. For the first time in a while, I can say that a large NW shift is fairly unlikely with this storm.
Likely helping us out with our accumulations will be favorable snow-to-water ratios. The typical snow-to-water ratio is 10 inches of snow for every 1 inch of water that falls, referred to as a 10:1 ratio. With this storm, ratios may start around 10:1, but will increase throughout the storm as cold air gets pulled into the storm, resulting in higher accumulation totals. (As a basic example [this won't necessarily be exactly what happens with this storm], if we got .5" of water falling with 10:1 ratios, that would result in 5" of snow. .5 of water falling with 20:1 ratios would result in 10" of snow.)
So, depending on the track of this storm, I could see anywhere from as little as 4" of snow (if we get dryslotted) to as many as 10" of snow (if we get the deformation band) falling in our area. As we get closer to the event, accumulations will obviously get locked in more than they are now.
Finally, on to the snow day chance. This will likely be a long duration storm, starting around noontime on Tuesday and ending sometime Wednesday morning. Currently, I'm focusing on Wednesday for the best chance of a snow day with this storm. For being 5 days out, I'm liking the chances of a snow day on Wednesday. For one thing, the timeframe is favorable, as it will still probably be snowing Wednesday morning. For another thing, considering the fact that it's February and we haven't had a snow day yet, I tend to feel that 5" or more will get us a snow day at this point. I also tend to feel that our area will probably get 5" or more with this storm, but at the same time, I recognize the fact that a lot can change between now and Wednesday, so I will conservatively put the initial snow day grade at a "C" (50/50 chance, things could break either way as we get closer to the event). I'm really liking this storm though.
Finally, for the first time in a while this winter, it appears that two systems will fully phase, allowing it to track further north than previous systems, and therefore affect us. The forecast models are in strong agreement on dropping an upper level low down from the Hudson Bay area and phasing it with a southern stream wave. This full phase will allow this system to track further north than the last two systems, despite another energy transfer occurring. This time around, the primary low pressure system will likely track from Mississippi to Michigan, before transferring energy to a secondary low that will move up the east coast.
What this means is that we will finally get some snow. And probably a decent amount of it, at that. The last four runs of the GFS model have been consistent in putting out a decent amount of precipitation for our area. Other models, such as the ECMWF and GGEM, are in agreement with our area getting a decent amount of snow out of this system.
Exactly how much snow we will get with this storm remains highly up in the air. If the low pressure system tracks directly over us, we will get dryslotted after the initial band of snow, which will cut down on accumulations. That was what the forecast models showed earlier, but they have trended a bit to the SE, putting us in the deformation band (heavier band) of snow, which would maximize our accumulations. The former is the worst option and the latter is the best option. The middle of the road option is that the low tracks even further to the SE, putting us out of the deformation band but also out of the dryslot. For the first time in a while, I can say that a large NW shift is fairly unlikely with this storm.
Likely helping us out with our accumulations will be favorable snow-to-water ratios. The typical snow-to-water ratio is 10 inches of snow for every 1 inch of water that falls, referred to as a 10:1 ratio. With this storm, ratios may start around 10:1, but will increase throughout the storm as cold air gets pulled into the storm, resulting in higher accumulation totals. (As a basic example [this won't necessarily be exactly what happens with this storm], if we got .5" of water falling with 10:1 ratios, that would result in 5" of snow. .5 of water falling with 20:1 ratios would result in 10" of snow.)
So, depending on the track of this storm, I could see anywhere from as little as 4" of snow (if we get dryslotted) to as many as 10" of snow (if we get the deformation band) falling in our area. As we get closer to the event, accumulations will obviously get locked in more than they are now.
Finally, on to the snow day chance. This will likely be a long duration storm, starting around noontime on Tuesday and ending sometime Wednesday morning. Currently, I'm focusing on Wednesday for the best chance of a snow day with this storm. For being 5 days out, I'm liking the chances of a snow day on Wednesday. For one thing, the timeframe is favorable, as it will still probably be snowing Wednesday morning. For another thing, considering the fact that it's February and we haven't had a snow day yet, I tend to feel that 5" or more will get us a snow day at this point. I also tend to feel that our area will probably get 5" or more with this storm, but at the same time, I recognize the fact that a lot can change between now and Wednesday, so I will conservatively put the initial snow day grade at a "C" (50/50 chance, things could break either way as we get closer to the event). I'm really liking this storm though.
HIGH confidence in a decent event Tuesday/Wednesday
Yep, that's right, I strongly believe we get a decent event on Tuesday/Wednesday this week. Very high confidence for being 96+ hours out...can't see too many ways this could bust for us.
I'll have a longer discussion up by noon tomorrow.
I'll have a longer discussion up by noon tomorrow.
Tuesday, February 2, 2010
Huge snowstorm this weekend...but will it affect us? Also, next week...
From a forecasting standpoint, it can only get better from here, because this weekend's storm features almost everything that can give a meteorologist a nightmare - most notably a sharp cutoff to the north edge of the precipitation shield, and an uncertain low pressure track which will cause a lot of uncertainty in the precipitation forecast, particularly for our area.
Having said that, let's take a look at what the forecast models are showing, and what I think will happen for our area. The models have come to a much better consensus from yesterday, and it now appears that of my 5 options, the one that will happen is... (4) A primary low pressure system tracking through the Ohio Valley, and energy being transferred to a secondary low pressure system which would either track up the East Coast or out to sea.
The thing that will make or break this storm for us is exactly when the energy will transfer. I'll try to explain this as best as I can...basically, the primary low pressure system will produce much of the snow for the Ohio Valley and Midwest, while the secondary low pressure system will prodcue much of the snow for the Mid-Atlantic and Northeast. Therefore, we want the primary low pressure system to make it as far north as possible before the energy transfers, so the snow associated with it also makes it as far north as possible. Once the energy transfers, the band of snow associated with it will stop moving north, and start moving east, which results in a sharp cutoff of snow accumulations. A difference of 50 miles in the track could result in us gaining or losing 6" of snow from this system.
Truly a forecaster's nightmare. So, when do the different models show the energy transferring? Currently, the results don't look all that good for us. I'll explain why they may change in our favor, and why they may not, but first, let's see what they show...
The 12z GFS has the primary low getting up to SE Kentucky before the energy transfers. Snow makes it up to the Ohio Border, more or less.
Having said that, let's take a look at what the forecast models are showing, and what I think will happen for our area. The models have come to a much better consensus from yesterday, and it now appears that of my 5 options, the one that will happen is... (4) A primary low pressure system tracking through the Ohio Valley, and energy being transferred to a secondary low pressure system which would either track up the East Coast or out to sea.
The thing that will make or break this storm for us is exactly when the energy will transfer. I'll try to explain this as best as I can...basically, the primary low pressure system will produce much of the snow for the Ohio Valley and Midwest, while the secondary low pressure system will prodcue much of the snow for the Mid-Atlantic and Northeast. Therefore, we want the primary low pressure system to make it as far north as possible before the energy transfers, so the snow associated with it also makes it as far north as possible. Once the energy transfers, the band of snow associated with it will stop moving north, and start moving east, which results in a sharp cutoff of snow accumulations. A difference of 50 miles in the track could result in us gaining or losing 6" of snow from this system.
Truly a forecaster's nightmare. So, when do the different models show the energy transferring? Currently, the results don't look all that good for us. I'll explain why they may change in our favor, and why they may not, but first, let's see what they show...
The 12z GFS has the primary low getting up to SE Kentucky before the energy transfers. Snow makes it up to the Ohio Border, more or less.
Hard to tell with the 12z ECMWF, but it appears to be more or less similar to the GFS.
12z UKMET, I had a better image with this but lost it, sends it a little north of the GFS and ECMWF, but not enough to make much of a difference.
12z GGEM, this is the best solution for us, sends the low all the way up to SE Ohio before the energy transfers. Precipitation shield goes up to I-69.
So, obviously the consensus is for the precipitation shield to stop around the Ohio Border, with us only getting minor accumulations, if anything at all. Here's some reasons why that may be wrong, and reason why that may be right:
Wrong:
*As the NAM forecast model comes into range, it appears to be headed for a more northern solution than the current model consensus. As I have said in earlier posts the NAM has been a pretty good model this winter.
*Overall, the models have trended further northwest from yesterday.
*As I have mentioned before, models tend to continue trending storms further northwest almost all the way up until the actually happen. We'll see if they trend even further northwest tonight.
*Sometimes, with an energy transfer, the forecast models tend to overdo how early the energy actually transfers, resulting in a further north precipitation shield.
Right:
*There is a strong model consensus right now, with 3 of the 4 major models that are in range agreeing in the precipitation field stopping at the Ohio Border.
*Can't go against winter trends. Almost all winter, the trend has been for less phasing and a more supressed storm.
*This one is a bit complicated, but effectively what you need to know is that there is a strong blocking pattern in place that will limit how far north the primary low can trend.
*A dry easterly wind will limit how much the atmosphere can be saturated with moisture.
Preference: I am in favor of a further NW trend with this storm. The models have trended significantly northwest since this time yesterday, and even with the more supressed storms this winter, the northwest trend has still appeared (it gave Washington DC a surprise storm last weekend). Combine this with the tendency of models to often overdo how early the transfer of energy occurs, and I think this will go further NW than currently forecasted.
Still though, it's going to be a close call. Based on model consensus, it would have to go ~ 60-80 miles NW to put us in business for snow from this storm. And with the blocking pattern and dry easterly wind, I question just how much further NW this storm can come. Combine that with the sharp cutoff in accumulations, and I see this as being a storm where accumulation forecasts will not be completely sorted out until we get within 12-24 hours of the storm actually happening.
Still, I will give us some accumulations probabilities with this storm (obviously subject to change)
Nothing: 20%
Trace-1": 20%
1-3": 40%
3-6": 15%
6+": 5%
Finally I'd like to say that if you only care about a storm for the snow days, then this isn't a huge deal, as it would likely be a Friday Afternoon - Saturday Morning storm if it affects us, and even if it does affect us, snow day criteria snow is not very likely.
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Beyond this storm, I hate to be looking at another storm a week out, but with this winter so far, what else can you do? As with earlier this week when I called for a big storm to affect part of the U.S. this weekend, signals once again look good for another big storm to affect the part of the U.S. There are a wide range of possibilities for this storm again...will it affect us? Stay tuned, as I'll probably start talking about it more in the next few days, as long as it still has a chance to affect us.
Monday, February 1, 2010
Meh...
As has been the trend all winter, the models have backed off from showing anything major happening to our area from a storm once it gets within the 5-6 day period.
Right now, IMO, besides the model analysis the main point of my discussion from yesterday stands, which is that there are still a wide variety of scenarios that can occur from this storm:
(1) No phasing, with the main storm being supressed well to the south.
(2) A partial phase, with the main storm going up the East coast but some moisture being thrown back towards us, resulting in minor accumulations.
(4) A primary low pressure system tracking through the Ohio Valley, and energy being transferred to a secondary low pressure system which would either track up the East Coast or out to sea.
(5) The main storm goes up the East Coast or out to sea, but we get some decent accumulation with a clipper system that moves through our area.
As it stands right now, the only one I would remove from the picture is #3, which unfortunately was the best scenario for our area. It still seems as though we could get an okay snow event this weekend, but it won't be anything too major.
I'll have a new, more detailed post tomorrow night...
Right now, IMO, besides the model analysis the main point of my discussion from yesterday stands, which is that there are still a wide variety of scenarios that can occur from this storm:
(1) No phasing, with the main storm being supressed well to the south.
(2) A partial phase, with the main storm going up the East coast but some moisture being thrown back towards us, resulting in minor accumulations.
(4) A primary low pressure system tracking through the Ohio Valley, and energy being transferred to a secondary low pressure system which would either track up the East Coast or out to sea.
(5) The main storm goes up the East Coast or out to sea, but we get some decent accumulation with a clipper system that moves through our area.
As it stands right now, the only one I would remove from the picture is #3, which unfortunately was the best scenario for our area. It still seems as though we could get an okay snow event this weekend, but it won't be anything too major.
I'll have a new, more detailed post tomorrow night...
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